mask not showing completely when rendering
I found a temporary solution but if somebody knows how to fix it definitely would be awesome.
I copied the splines of the frame 147, created a new mask and paste to render frame 148 and it works.
Once the mask is created go on the node compositer and change the name of the previos mask for the new one. As it is copied for the previous frame you may need to do minimal position changes.

It doesn't work by just changing the mask. It is necesary to unplug the mask node, change the name of the mask and then plug it again.

Save the rendered image as a PNG file, separated from the rest and add it later to the image sequence to create the video clip.